Organosilicon compounds and process for their preparation



United States Patent 3,193,567 ORGAWQSILICON COMIGUNDS AND PRKKJESS FGR 'rrmm PREPARATIGN Gard Rossm Altendorf (Ruhr), Germany, assignor to Th. Gcidschmidt A.G., hemische Fabriiien, Essen,

Germany, a German corporation No Drawing. Filed Aug. 22, 1961, Ser. No. 133,040 Claims priority, application Germany, Aug. 30, 196%,

G 39,393; Feb. 27, 1961, G 31,708 36 Claims. (Cl. 260448.8)

My invention relates generally to o-rganosilicon compounds and is particularly concerned with cyclic and polymeric siloxaalkanes and processes for their preparation.

In recent years, organosilicon compounds, which may be designated as condensation products of silicon compounds having organo-functional hydroxy groups and silanols, have gained importance and recognition to an ever increasing extent. Of particular importance and interest are, in this connection, compounds which may be considered formed from-partly hypothetical-monomolecular organosili-con compounds wherein the Si-atom has attached thereto at least one hydroxy-substituted alkyl group and at least one directly bonded hydroxyl group. Such polyfunctional silicon compounds, by condensation, are capable of forming cyclic compounds 0 or polymeric compounds of linear or cyclic structure corresponding to the formula In these formulas, M stands for a divalent substituted or unsubstituted hydrocarbon group.

Several processes yielding such compounds have become known in recent years. However, these prior art processes have several serious disadvantages and shortcomings. The primary reason that the prior art processes have not been generally accepted by industry is that the starting materials for these processes are bydroxyalkyl silicon compounds which are not readily available. Further, the hydroxyalkyl silicon compounds which may successfully be utilized in the prior art processes are limited to those species wherein the residual free valences of the silicon atom, as indicated in the Formulas A and B above, are exclusively saturated by or attached to alkyl or trialkylsilylhydroxy groups which are slow to react and are no longer capable of linking.

It is a primary object of my invention to overcome the drawbacks of the prior art processes by providing a novel process for preparing compounds of the kind referred to, wherein readily available starting substances are used, and wherein the hydroxyal'kyl silicon compounds which are not readily available are merely formed as intermediates which nee-d not be isolated.

It is also an object of my invention to provide for a process for the preparation of the compounds of the kind referred to, wherein the reaction gives almost quantitative yields.

A still further object of my invention is to provide a process of the kind referred to which permits the in- "ice corporation of additional reactive groups linked to the silicon atom.

It is also an object of my invention to provide novel organosilicon compounds which have a wide utility and application for industrial use.

Generally, it is an object of my invention to improve on the art of organosilicon compounds and processes for their preparation as hitherto practiced. The starting materials for carrying out the inventive process are organosilicon compounds of the general formula In this formula:

R, R and R stand for the same or different substituted or unsubstituted hydrocarbon groups. Such hydrocarbon groups are, for example, CH C H C H O'C H4Cl, 1,3-C3H6CN and 1,4-C4H Cl;

Generally, R, R and R" may stand for alkyl, aryl, alkaryl or aralkyl;

M is alkylene with at least two carbon atoms, as for example C H C H C H or 1,-3-C H Cl;

n and m are numbers defined by n=02, m=1-3, and (n+m)=3.

Preferred groups for R and CH and CgH while CH and C H are preferably chosen for R and R".

Such silicon compounds may be readily prepared by, for example, forming an addition product of esters of unsaturated alcohols with the corresponding SiH compounds. Such addition may be performed according to well known processes.

It is also within the scope of the inventive process to employ starting compounds of Formula C which have been obtained by first preparing the corresponding halosilane wherein X stands for halogen, preferably C1, and wherein the other symbols have the above-defined meaning, and thereafter converting this halo-silane into the desired starting compound of Formula C by reaction with an alcohol, preferably in the presence of an acid acceptor as, for example, ammonia, sodium ethylate, triethylamine or pyridine. In many cases it will not be necessary to purify the starting compound as, e.g., by distillation.

According to the inventive process, an alcohol is added to the starting compound of Formula C referred to. In doing so, it is advantageous to choose the alcohol which corresponds to the OR group of the starting compound.

Moreover, a reesterification catalyst known per so, such as for example, sodium alcoholate, potassium alcoholate, sulfuric acid, HCl, trichloroacetic acid or trifluoracetic acid is added.

For the purpose of initiating the reaction, it is sufli cient to add but traces of alcohol. However, in many instances it is advantageous to add a larger excess of alcohol, for example, about 0.1 to 2 moles of alcohol per mole of MO-ii-R group.

The amount of required catalyst is within the same order of magnitude as in other reesterification reactions 3) 7 generally known from organic chemistry, i.e., for example 0.014%.

I do not wish to be limited to any theories advanced by me; however, I have reason tobelieve that the reactions in accordance with the inventive process proceed according to the following formulas:

If the alcohol and ester are removed by distillation, then, it may be fairly statedithe reesterification reaction is completed in one single'stage, because the organosilicon alcohol by condensation is continuously withdrawn from the equilibrium condition. A viscous or in some instances solid polymeric mass is obtained as the final product. Thismass constitutes the desired condensation product This polymeric reaction product may be purified in exceedingly simple manner by converting it into the cyclic substance The conversion of the polymeric mass into the readily volatile cyclic substance is easily accomplished by heating to 50-400 C. The conversion into the cyclic substance is facilitated by operating under subatmospheric conditions during the distillation and possibly by the presence of an alkaline or acid catalyst which, of course, i already present in the polymer substance in the form o a r s due, of t c aly t, r ma nin rom he reesterie fi atio p pe The m u f su h catalys Should P e e ab y e Dil -5% a d gen rally the same atalyst a du in he e r ca icn P ope a h use pre erably, however, alkali metal hydroxide or alkali metal alcoholate or alkali silanolate. The cyclic substances obtained in this manner are water-clear'liquids of extraordinary reactivity yvhich, in many instances, already during condensation from the vapor state again partly 'nclym 'i z Gsmraflrr th e cycli sub t c s o espend to the general formula wherein the various symbols have the above given meaning and values. f 7

Very little is known concerning the structural build-up of these polymeric products. In particular, it is not certain which terminal groups limit the linear polymers. It would, of course, suggest itself that such terminal groups are constituted of OR groups or OH groups which could emanate from alcohol or water traces present in the polymer structure. Many properties of these polymer products tend also to point to higher molecular ring systems.

Polymerization and depolymerization take place with out the use-of; catalysts. Thus, 1-ethoxy-1-methyl-1,2- siloxacyclopentane which polymerized on its own account to high viscous fluids or gels may be distilled without difiiculties and without the addition of a catalyst. Depolymerization takes place not only during heating, but also upon dissolution of the polymeric substance in an inert solvent. Such depolymerization may thus be effectively observed by, for example, infrared spectroscopic methods in solvents such as CS CCl CHCl and the like. Thus, for example, for the system of the 1-2-siloxacyclopentane derivatives an intense band at 1035 cm.- is particularly characteristic for the 5-ring cyclic compound, while the higher molecular units can be easily recognized at a band of 1195 cm.

The process hereinbef ore described may be carried out in simple manner and gives excellent yields. Nevertheless, in those instances in which the OR group constitutes the alkoxy residue of an alcohol which is available with difficulty only or which is expensive, the process is not entirely satisfactory as it results in losses of such alcohol.

In further development of the invention, it is therefore preferred in those latter instances first to prepare R' 1 (Mo) wherein the OR group represents a readily available alkoxy group such asmethoxy, ethoxy or propoxy, wherethe original starting material.

after, in a second step, a reesterification reaction with the more expensive and higher boiling alcohol or phenol R OH is performed. In this formula R designates a hydrocarbon which is different from the starting sub-. stance wherein, however, R has the same meaning as in The reesterification reac-. tion is catalytically induced by means of well known catalysts known to chemists skilled in the art as, for example, alkali metal hydroxides, alkali alkoxides, sulfuric acid, tn'chloroacetic acid or trifluoracetic acid. Also, the amount of catalyst corresponds to generally known procedures, that is, it will be about 0.0l-5% by weight. Sodium or potassium-alcoholate is a particularly preferred and simple catalyst.

The reaction proceeds quantitatively or at least almost quantitatively, while the more volatile R'OI-I is distilled off. The distillation'may be performed through a column. The compound obtained by the reesterification may be readily purified by distillation in its cyclic form.

The inventive cyclic or polymeric liquids lend themselves particularly Well to reactions with isocyanates, with alkyd resins for the preparation of mixed resins, with carboxylic acids forthe production of acylhydroxyalkyl-substituted siloxanes or for the preparation of modified silicon polymers. However, this does not limit the use of the inventive compounds as, for example, they may be incorporated or built in a very simple manner into other organosiloxanes while using known equilibration catalysts.

If the compounds are reacted with or sulfuric acid, Water soluble silicon-organic sulfuric acid esters are obtained. i

The invention will now be described by several examples, it being understood, however, that these examples are given by way of illustration and not by way of limitav tion, and that many changes and alterations may be effected in choice of, e.g. starting materials and process conditions in general, without departing in any way from the scope and spirit'of this invention as recited in the appended claims.

' EXAMPLE 1 6459 grams of ry-acetfixyprQpylmethyldichlorosilane were added in dropwise manner to a mixture comprising liters of benzene and-3Q4Q-gran1s of ethanol. The mixture was saturated with ammonia and during the.

dropwise addition of the silane compound, ammonia was constantly introduced into the Well-stirred reaction miX ture. Ammonium chloride precipitated, was filtered OE and dissolved in water. In doing so, a layer of ethoxysilane separated, which was taken up with a small amount of benzene, was dried and thereafter added to the filtrate. Upon removal of the benzene by distillatiomthe 'y-acetoxypropylmethyldiethoxysilane formed could be recovered in pure form by means of fractional distillation. 6550 grams, which corresponds to about 94% of the theoretical amount, distilled at 13 mm. Hg between 108 and 112 C. The other alkoxysilanes mentioned in the subsequent examples could be recovered in analogous manner with similar yields. 4680 grams of the compound 'y-acetoxypropylmethyldiethoxysilane thus obtained were admixed with 460 grams of anhydrous ethanol and grams of sodium and the mixture was left to stand over night. The ethylacetate which was formed and excess alcohol were removed by distillation, and the reesterification process was thereafter repeated once more with a further amount of 460 grams of ethanol. The ethylacetate-ethanol mixture was separated whereupon the remainder was subjected to distillation at 150-170 C. whereby 2730 grams of a liquid were obtained which corresponded to about 94% of the theoretical amount. This liquidv was subjected to infrared spectroscopic analysis which clearly indicated that it consisted of l-methyl- 1 ethoxy 1,2 siloxacyclopentane comprising a small amount of methyltriethoxysilane. This liquid, upon standing, became more viscous to change over into its polymeric chain-like state. Upon fractional distillation through a column of 30 cm. length which was filled with filling bodies, the main portion, i.e. more than 90%, distilled between 159 and 162 C. Infrared spectroscopic determination clearly indicated the absence of methyltriethoxysilane after the distillation. The spectrum of the gaseous substance exhibited, in addition to the known absorptions characteristic for the SiCI-I and the SiOC H groups, a very characteristic intense band at 1035 cm.- for the 1-2-siloxacyclopentane ring. A test sample which was freshly distilled and which had been separated at -70 C. was subjected to cryoscopic molecular weight determination which indicated the value 160, while the theoretical value for the cyclic monomeric substance is 146. A portion of the substance was in crystalline form at 70 C. Elementary analysis yielded the following values:

Analysis Actual Theoretical s1 18. 9% (19. 2%) O 49. 0% (49. 3%) H 9. 9% 9. 65%) 002115 30. 6% (30. 8%)

The liquid rapidly polymerized upon heating to room temperature. After standing for days at C., the viscosity increased, for example, to 55 op. The polymerization may be considerably accelerated to a certain optimum point by traces of moisture, alcohol, acids, Friedel-Crafts catalysts, many other metal salts and higher temperatures. The polymerization may be constantly interpreted and its course may be checked and observed. This may be done by means of the viscosity and the infrared spectrums which will show an increase of the band at 1195 cmr and a decrease of the band at 1035 cmr In this manner, liquids having a viscosity of several thousand cp. may be readily prepared. Even samples which have already solidified into gel form may be readily depolymerized upon heating to temperatures in excess of about 160 C. and may then be distilled in the form of the monomeric cyclic compound. 7

The operating method described hereinabove was ap plied in analogous manner to other alkoxysilanes as disclosed in the following examples. The operating and process conditions, however, could be varied within broad limits with regard to the amounts of alkali metal and alcohol, as well as concerning the reesterification temperature, without there being observed significant changes in the reaction course. The yields were throughout almost quantitative. For the purpose of avoiding side reactions, it was, however, in some instances advantageous to employ very small alkali and alcohol amounts and to neutralize the alkali catalyst prior to the distillation of the cyclic compound. Such undesired side reactions would cause a splitting of the Si(CH bond.

In the following examples, the alcohol and alkali amounts per mole of ethoxysilane as well as the reesterification temperature are indicated in each separate case.

The structure of the compounds obtained was confirmed in each case by elementary analysis and infrared spectroscopic measurements. With regard to the polymerization, all the 1,2-siloxacyclopentanes prepared exhibited in principle a behavior corresponding to that of 1- methyl-l-ethoxy-1,2-siloxacyclopentane.

EXAMPLE 2 Preparation of I-mezhoxy-I-methyl-I,Z-siloxacyclopentune Quantities of starting materials:

1 mole of 'y-acetoxypropylmethyldimethoxysilane 1 mole of methanol 0.6 gram of sodium The reeesterification was carried out at room tem- Quantities of starting materials:

1 mole of alkoxysilane 0.7 mole of n-propanol 0.5 gram of potassium The reesterification was carried out at C. Yield: 86%. Boiling temperature: 177181 C.

Analysis Actual Theoretical EXAMPLE 4 Preparation of 1-i-but0xy-1-methyl-],2, siloxacyclopenmne Quantities of starting materials:

1 mole of alkoxysilane 1 mole of i-butanol 0.7 gram of sodium The reesterification was carried out at room temperature. Yield:.94%. Boiling temperature: 187-193 C.

Analysis Actual Theoretical Actual Theoretical Analysis Actual Theoretical EXAMPLE 7 Preparation of 1-1-dieth0xy-1;2-siloracyclopentarre Quantities of starting materials: 1 mole of alkoxysilane 0.7 mole of alcohol 1 gram of sodium The reesterification was carried out at room temperature.

alkali was neutralized with acetic acid. Yield: 90%. Boiling temperature: 225-230 C.

Analysis Actual Theoretical EXAMPLE 8 Preparation of 1,1 -dimethyl-1,2-siloxacycl0pentaae' The quantities of starting materialswere the same as in Example 1 Reesterification was carried out at room temperature. Yield: 91%. Boiling temperature: 109- 113 C. v

Analysis Actual Theoretical v 5 Prior to the distillation of the cyclic substance, the

EXAMPLE 9 V Preparc ztion of 1-'m'et hyl 1-ethoxy-1,2-sil0xacycl0hexane Quantities of starting materials: 5 1 mole of alkoxysila'ne 2 moles or ethanol 7 1.6 grams of sodium The reesterification was carried out for one hour at 10 80 C. Yield: 95%.. Boiling temperature: 165-173 C.

Actual Theoretical i In contrast to the siloxacyclopentane deriyatives. the substance did not polymerize upon simple standing.

' EXAMPLE 10 Preparation 0 1'-"methyl-1-'phenoxy 1,2-siloxacyclopfitafie 1. mole of l-methyl-l-ethoxy-1,2-siloxyclopentane in predominantly polymeric form, 1.1 mole of phenol and 1 gram of sodium were mixed and heated in a flask connected with a -column. 43 grams of ethanol distilled over. which corresponds to about 93% of the theory. The residue could be distilled at temperatures up to 260 C; In doingso, 185 parts by weight distilled, which corresponds to about 93% of the theory. The bulk distilled after repeated fractional distillation between 255 and 257 C. i

Analysis Actual The oretical 14.3 14.45 V 2- ii-2 4.0 0 Y EXAMPLE '11 The reesterification reaction described in Example 10 was performed in analogous manner with diethyleneglycolmonome'thylether. 1,2'-( 2"-methoxyethoxy)-ethoxy-1- m'e'th'yl-l,2-siloxacyclopentane was obtained in a yield of about 75%. Boiling temperature: 1'1'5440" C., 0.2. mm.

Analysis Actual Theoretical EXAMPLE 12 Preparation of 1 -n-0ct'0xy'-1 m rtyr-1 ,2-sil0xacyel0pentane The reestierification described in Example 10 was carried out in analogous manner with n-octanol. After expelling the ethanol, the residue distilled at 140-155 C. at 11 mm. Hg. The product obtained solidified into a wax-like mass upon cooling.

Actual Theoretical EXAMPLE '13 1 mole of l-methyl-l-ethoxy-1,2 siloxacyclopentane in predominantly polymeric form was heated with l mole 7 of glycol and 0.4 gram of sodium. In doing so, 1 mole of ethanol distilled. The residue was a viscous liquid. The infrared spectrum indicated the presence of chains and hydroxyl groups.

EXAMPLE 14 Preparation of l-trimethylsiloxy-1-methyl-1,2- siloxacyclopentane distilled at 155165 C.

Analysis Actual Theoretical Also the previously described propoxy-, butoxyand hcxoxyderivatives of l-methyl-1,2-siloxacyclopentanes can be prepared by reesterification from l-methyl-l-ethoxy(methoxy)-1,2-siloxacyclopentane in simple manner.

EXAMPLE 15 Within 5 hours a solution of 1 gram of potassium in 46 grams of ethanol was introduced in drop-wise manner at a temperature of 105 C. into 234 grams of 'y-acetoxypropylmethyldiethoxysilane. Upon vigorously stirring besides ethanol 97% of the theoretical amount of ethylacetate distilled off. Thereafter the residue was freed from the catalyst by filtration and was distilled at 25 torr in a vaporizer working with a thin layer being heated to 150 C. 136 grams (93% of the theoretical amount) of 1- methyl-1-ethoxy-1,2-siloxacyclopentane were obtained as a distillate.

What I claim is:

1. Organosilicon compounds of the unit formula wherein R and R stand for hydrocarbon groups; M is selected from the group consisting of alkylene and 1,3-C H Cl; and n and m are numbers defined by 2. Organosilicon compounds of the unit formula wherein R and R are each members selected from the group consisting of alkyl, aryl, alkaryl, o-C H Cl, 1,3-C H CN, 1,4-C H Cl and aralkyl; M is selected from the group consisting of alkylene and 1,3-C H Cl, and

claim 2,

claim 2,

l6 7. Organosilicon compounds as set forth in claim 2, wherein the compounds are in their polymeric form comprising at least two Si-atoms.

8. Organosilicon compounds of the unit formula wherein R and R stand for lower alkyl; M stands for (CH wherein x=34; and n and m are numbers defined by 9. Organosilicon compounds of the unit formula wherein R is CH R is lower alkyl; M is (CH and n and m are numbers defined by n=0l, m=2-3, and (n+ m)=3.

l0. Organosilicon compounds of the unit formula X0 GHFOHQ Cfia 0- H wherein X is alkyl.

11. Organosilicon compounds of the unit formula X0 CH2GH3 S1\ XO/ 0--- H2 wherein X is alkyl.

12. A process for the preparation of Organosilicon compounds of the unit formula wherein R and R are each selected from the group consisting of alkyl, aryl, alkaryl, o-C H Cl, 1,3-C H CN, 1,4-C H Cl and a-ralkyl; M is selected from the group consisting of alkylene and 1,3-C H Cl; and n and m are numbers defined by which comprises admixing organosilicon compounds of the formula wherein R" is selected from the group consisting of alkyl, aryl, alkaryl and aralkyl and the other symbols have the above defined meaning, with an alcohol of the formula ROH and a reesterification catalyst, and separating the resulting ester RCOOR and the excess amounts of the alcohol ROH by distillation.

13. A process as claimed in claim 12, wherein said compound 0 (RO)mRnSi(MO .'iR") is a v-acetoxypropyltrialkoxysilane.

.14. A process as claimed in claim 12, wherein said compound "17'. A process as claimed in claim '16, whereingthe monomeric product is distilled to obtain a cyclic product comprising a single Si-atom. p

18. A process as claimed in claim 17, wherein said distillation is carried out. under subatmospher-ic pressure conditions.

19; A process as claimed in claim 17, wherein said distillation is carried out in the presence of a depolymeriza- 7 tion catalyst.

20. A process as claimed in claim 19, wherein said depolymerization catalyst is the same as the catalyst employed as the re-esterification catalyst.

2/1. A process as claimed in claim '12, wherein the reaction product er unit formula 7 is reacted .With a compound ROH whose boiling point is higher than the boiling point of the alcohol corresponding to the OR group of the above formula, said reaction being carried out in the presence of a reesterification catalyst, and removing the lower boiling alcohol by distillation. V y

22-. A process as claimed in claim 21, wherein said catalyst is an alkali metal alcohol-ate.

23. A process as claimed in claim 21, wherein the reaction product obtained after said distillation is depolymerized by heating it to about 50-400" C.

24. A process as claimed in claim 21, wherein the reaction product "obtained after said distillationis depolymerized by heating it to about 50400 C. and is then distilled to obtain a cyclic product comprising a single Siatom.

25. Organosilicon compounds of the unit formula wherein X is aryl.

26. Organosilicon compounds of the unit formula wherein X is Z-me-thoxyethyl.

27. Organ-osilicon compounds of the unit formula wherein X is 2-(2'-methoxyethoxy)-ethyl.

28; Organ-osilicon compounds of the unit formula 20 wherein X is 2-methoxyethyl.

30. Organosilic-on compounds of the unit formula X0 carom wherein X is 2-(2-methoxyethoxy)-ethyl;

References Cited by the Examiner UNITED STATES PATENTS 3/42 Rot-brook 260448.8 2/59 Barnes 260448.8 5/59 Bailey 260-448,8 10/59 Shibe 2 60.448.8 5/61 Knoth 260-4483 5/61 Speier 260448.8

OTHER REFERENCES Speier: Jour. Am. Chem. Soc, vol. 74 (1952), pp.

40 oos-1o.

TOBIAS a.

ALPHONSO. D. 'SULLlVAN, SAMUEL IJEVOW, Primary Examiner.

H. BLECH,

Examiners. 

1. ORGANOSILICON COMPOUNDS OF THE UNIT FORMULA
 12. A PROCESS FOR THE PREPARATION OF ORGANOSILICON COMPOUNDS OF THE UNIT FORMULA 